Journal of Animal Research and Nutrition

Table 2: Quantities of nitrogenous matter intake for the four lots.

Part of morphological characterization

The sampling

The used samples of Medicago come from farm of Oued- Smar and managed as previously announced. Sampling for fodder analyses in green is carried out in second and third cycle on the same culture of Medicago.

That is why we have delimited to studied stages (floral buds: FB) four micro plots of square meter (Figure 3) at different places of the Medicago stands. One of the micro plot is intended to the determination of report of leaves on stems.

Figure 3: Delimitation of a square meter in the alfalfa.

The three other micro-plots have been the subject of measuring biometric parameters that are related to the nutritional value of forage and yield rating after mowing.

Biometric parameters

The biometric parameters studied are components of yield in relation with variation of chemical composition of fodder which are, number of plants by square meter, number of stems by square meter, stems diameter, the report in dry and in green on stems, length of stems, and yield in green and in dry.

Chemical analyses

The focused on dry matter (DM) by passing in oven of 3 g of the ground matter at 150°;C; parietal constituents (NDF, ADF, ADL) by method of Van Soest; the total nitrogen matters (TNM) by Kjeldhal method; the raw cellulose by method of Weende (CBw) and so mineral matter (MM) by incineration in calibrated into muffle furnace set at 550°;C. Calcium and phosphorus are determined by atomic absorption.

Statistical analyses

The results obtained made subject of statistical analyses with calculation software stat view and statistica 1987.

Results and Discussion

Yield depends of the plant growth, but also of the number of plants by surface unit and number of shoots [2]. And so the number by square meter found in triad variety at flowing ud is an average of 11.78 plants by m².which corresponds an average of stems number of the three sections of 142.12 stems by m² (Table 3).

Table 3: Biometric parameters of triad Medicago.

The factor which determines growth of the plant is the average height of stems. At the bud stage, it is of 69,45cm (Table 3). Average yield of the three sections by square meter, at this height and at this stage, is of 1795,556 g/m² against 447,83g /m² de DM with a report leaves on stems of 0.95 in green and of 0.79 in dry (Table 3).

Diameter of the stem at adult age is a varietal character. Stems’ fineness is sought after for Medicago intended to wither. In the same plant, evolution of diameter is according to phenological stage.

At budding stage, the average diameter of the three sections is of 0.215 cm (Table 3). The chemical composition given by Table 3, shows content in TNM of the triad at flowering bud (FB) between 15.5% and 17% of the DM.

This value is low with result given by Mauries [2] which can vary of 14 and 29% of DM according to stage and cycle of the section. This weak content may be explained by cycle number of the plant (3RDcycle) since according to the same author, at the second cycle content decreases with age of shoots but more slowly than in the first cycle .

The quantity in ash of triad Medicago varies between 6.547 and 7.011% DM (Table 4). These values are low to those given by Meschy and Gueguen [3] which constitute 8 to 15% of dry matter of fodder with a general manner.

Table 4: Chemical composition (in % of DM) of the Triad variety.

As for this chemical element, it seems having opposition between minerals accumulation and the full growth of vegetative organs which is followed by an active polymerisation of carbohydrate.

Thus, age influences on quantity of minerals found in the plant. Furthermore, Medicago includes a combination particularly interesting of minerals and oligo elements.

Professor Van Belle, of University of Louvain in Belgium reports experimentation on sheep in which addition of calcined Medicago, which that means containing only minerals of Medicago, allowed to double microbial synthesis in the rumen [4].

Contents recorded in calcium at the triad of the same stage vary between 1.52 and 1.59% of DM. Content given by Daccord et al. [5] in leguminous is of 1.51 ± 0.25% MS .These last ones increase with age advancement. However, we record contents in phosphorus varying between 0.324 and 0.328% of DM (Table 4), which are identical values to those given by Daccord et al. [5] comprise between 0.34 and 0.36 of DM. Content in minerals of the plant is reflecting of the soil which produces it [6]. Phosphoric liquid fertilizers seem provoking a more substantial increase of content in P of fodder [3].

According to Chadjaa [7], phosphate fertilizers have a positive effect on accumulation rate of total nitrogen in plants, and so on rate of totals proteins. In our Medicago plot, no report of P has been done. Results of cellulose found give an average for the three sections made of 26.087% of DM (Table 4).These values agreed with results of some authors (INRF, 1998; ITEBO) on a Medicago harvested at the same stage. Average content in NDF given by the three sections is of 43.31% of DM (Table 4), which are identical values with those of Piva et al. [8] at stage 3and Corsi et al. [9]. As for content in ADF, it is of 25.26% of DM (Table4) and similar to result of. Torricelli et al. [10]. The chemical element, lignin, as determinant for digestibility in ruminants is an average of 9.36% DM for the three sections at budding stage (Table 4).Variance analysis of parameters studied at bud stage (details in Annex 1) shows a difference highly significant (P < 0.0001), to significant (P < 0.05), between the three sections on all parameters measured except for mineral (MM) of Medicago of the three sections which shows no significant difference that high distance decrease lignin rate of the plant.

The Principal Component Analysis (PCA) of parameters studied allows us to say that criterion of Kaiser let us to retain an axis. Projection of parameters studied (Annex 2) shows that all studied elements are located at the level of circle periphery. We can conclude that all parameters are highly correlated with parameters constituting this plan (1 and 2). This factorial axis gives 100% of information (79.07% + 20.93% = 100%), the axis according to which is preserved by projection the maximum of spreading of cloud’s points The maximum angle between tow variables of a same plan is low at 90°;. That suggests that all variable are positively correlated between them. Sampling is made in third circle of Medicago stands’ life.

The first section is done on 19/04/2012. Projection of factor studied number of section at bud stage (Annex 2) show that the most chemical parameters (ADF, NDF, RB, TNM, CB) and diameter of stems are opposing to phosphorous and lignin quantity. The last two parameters have contributed to locate the first section in this axis. Germination density (number of plant m²), yield in dry and in green and average stems’ height locate the second section made on 7/05/2012 in the same axis. The quoted factors are opposing parameters leaves report on stems in dry and in green and the last ones locate the third section made on 28/05/2012 in this axis.

The report showed from the first section of the spring beginning that we can vary number of stem by m² by increasing seeding density or space between plant to decrease rate of lignin in stems (both parameters are negatively correlated). However, seeding density depends closely of germinal capacity of the variety. The yield variation in green and in dry depends of number of plant by square meter and average height of the stems at this stage.

The number of plant by square meter decreases with age of Medicago regardless of seeding dose and space between lines. So the second section in spring at this stands Medicago age depends on installation conditions of Medicago stands. At spring end and at summer beginning, among all parameters studied, those are reports leaves on stems in green and in dry which justify value of the third section. The chemical composition of Medicago hay is characterized by contents in DM and in OM respectively of 90.6% and of 87.93% (Table 5).

Table 5: Chemical composition of food distributed to sheep.

These values are close of those obtained by Kamalak et al. [11] with respectively 93% and 88.9% on average of 14 different varieties of Medicago hay. Content in mineral matter is enough high (12%; Table 5) according to results obtained on the green triad at the same stage. That may be explained by presence of ground in hay after its baling.

Content in TNM obtained in hay is of 12.6%, it is weaker compared to 16.8% obtained by Chibani [12]. Presence of weeds, drying conditions, lost of leaves during gathering of hay; stage and number of plant cycle are other factors of variations which can explain this difference. Furthermore, although contents in nitrogen in green found vary between 15 and 20% of DM, it is logical that content in hay nitrogen be low to 15% of DM.

Results concerning the coefficient of digestibility (DWC) in dry matter obtained during measure phase with triad hay at budding period are of 61.4% (Table 6). It is acknowledged that digestibility decreases with increase of fodder’s content in dry matter [13]. This increases with growth of physiological stage of the plant.

Table 6: Apparent digestive working coefficient of DM, OM and of TNM (in %).

The triad hay organic matter of budding stage offers a DWC of 69% (Table 6), this digestibility is inversely proportional to lining content, [14] cells contents are most digestive. As for hay TNM of the triad, we recorded weak digestibility with an average on animal lot of 55.5%. The apparent digestibility is weaker compared to real digestibility of fodder’s nitrogen matter. In effect, faeces contain substances endogenous and microbial whose quantity is proportional to the quantity of dry matter ingested [15].

Conclusion

The chemical composition of Medicago studied shows that content in ash is weak that is perhaps because of absence of soil fertilization. As for content in TNM, it varies between15.5 and 17.04% of DM which is low to values usually given (INRA, 2007) but that can be explained by number of cycle growth of the plant. Contents in fibers, raw cellulose, ADF and NDF agree with those given by authors which did not modify digestibility of the species.

However, the chosen season of sampling does not mark influence of these parameters in PCA. The determinant chemical component for digestibility, lignin offers us an average of 9.36% of DM.

This content can be decreased by genetic handling and would increase then DWC of the plant. The average of chemical factors studied, of the three sections of the Triad Medicago stands, in spring of its third cycle, corresponds to average value of the third section. The yield in green and in dry offers an average respectively of 1795,56 g/m²; et 447,83 g/m²;. So it is more logical to measure fodden dry than in green to quantify the dry synthetized matter and non water quantity retained to a given stage since this one evolves with plant age. For the most parameters studied analysis of variance is either significant or highly significant. This shows there is a variation from a section to another within parameters studies in the plant, except MM which a parameter linked much more to the soil than to the plant.

Several correlations are recorded between parameters studied, which is more striking is that r = 1 between both minerals (Ca, P) and NDF and so between number of plant and content of lignin. This observation will allow to the far the immediate action on seeding dose and space between lines to decrease rate of lignin in the plant. The principal components analysis, separates the three sections of the same stage in different axes of the single plan formed in this analyse. The chemical composition of Triad hay in budding stage does not show notable differences compared to Medicago hays already studied outside of content in TNM which is slightly weaker. The Digestive Working Coefficient of OM and TNM is respectively of 69% and 55.5%, which is relatively weak for TNM. Finally, multiplication of essays on the same fodder according to years and harvest regions is necessary in order to have more reliable and accurate average values.

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